Carburetor



Sept. 4, 1934.

C. LORENZEN I GARBURETOR Filed Aug. 26, 1931 2 Sheets-Sheet l INVENTOR CH215 T/AN L o/ez/vzs/v Q/ K, W ATTORNEYS lIfII/llllllffllll PatentedSept. 4, 1934 CARBUBETOR I Christian Lorenzen, Berlin-Treptow, GermanyApplication Augilst 26,1931, Serial No. 559,388

' In Germany January 9, 1931 8 Claims. (Cl. 261-44) My invention relatesto carburetors for internal combustion engines, and has for its objectto provide an arrangement by which the supply of air will always be inproper proportion to the supply of fuel irrespective of the varyingconditions. Another object of the invention is to provide a simpleconstruction having a single air supply channel of the Venturi type andtwo parts connected to move in unison, one of saidparts 10 controllingthe passage of air, while the other part controls the passage of fuel.It is wellknown that the explosive or power-producing effect'of afuel-and-air mixture is the greater, the more thoroughly the fuel hasbeen mixed with the air and the more accurately the correct ratio ismaintained between the weights of these two media. Special diflicultiesare encountered in securing this desirable result when the mixture isfed to the engine with the aid of a compressor or so-calledsupercharger, since such a device supplies the mixture under afluctuating pressure, and one of the objects of the present invention isto overcome these diificulties. A carburetor embodying my invention willoperate equally well whether the engine is of the customary suction typeor whether -a supercharger is employed in conjunction with the engine.With my invention, a practically constant suction effect is obtained atthe fuel spray nozzle, irrespective of whether the engine is running atno load or at full load and also irrespective of the position assumed bythe customary throttle valve interposed between the spray nozzle and theengine proper. V g

In order to obtain a practically perfect atomizing or spraying of theliquid fuel even when employing alcohol or heavy crude oil, and toinsure an intimate mixture of the fuel with the air, I have devised anovel method of operation, ac-

cording to which the energy of the air flowing to the engine by suctionhas a duplex action for atomizing or spraying thefuel. This duplexaction consists, first, in causing the fuel or the fuel mixture to bedischarged, through a series of distributing nozzlesyby the applicationof pressure within the fuel-supply tube; second, in causing t the jetsissuing ,from said nozzles to meet a current of air which streams pastsuch nozzles, said current of air exerting a suction effect and break- 53 ing up or further atomizing said jets, so that the two atomizing orspraying actions assist and reinforce each other.

It is well-known that difilculties in carburetor action, which becomeperceptiblein irregular operation of the engine, always arise duringchanges of speed, and also when the engine is running at low speed or isbeing accelerated, but do not exist at all, or only to a very slightextent, when the engine is running under full load or at relatively highspeed. The reason for this is that in the latter case the fuel issues ata high speed, resulting in eflicient spraying or atomizing andconsequently in a thorough mixture of the fuel with the air. With mypresent invention, good atomizing and eflicient mixture of fuel with airare obtained even under unfavorable conditions such as hitherto wouldhave caused the engine to falter or even stall.

The novel features of the invention will appear more fully from thedescription following hereinafter, and will then be specifically pointedout in the appended claims.

Four typical and satisfactory embodiments of my invention areillustrated by the accompanying drawings, in which Fig. 1 is a centralvertical section through a float-type carburetor pro-' vided with myimprovements; Fig. 2 shows upon an enlarged scale, in axial section, thespray nozzle illustrated in Fig. 1; Fig. 3 is a plan view of such spraynozzle; Fig. 4 is a central vertical section through a form of myinvention in which no float is employed; Fig. 5 is a similar view ofstill another floatless form of my invention; Fig. 6 is an enlargeddetail view of a portion of Fig. 5; Fig. 7 is a vertical section'throughanother em 5 bodiment of my invention; and Fig. 8 is a horizontalsection on line 88 of Fig. '7.

In Fig. 1 a is the mixing chamber and b the float chamber which areconnected with each other rigidly and may form a unitary casing. At b Ihave indicated the fuel inlet connected with the float chamber 1) by apassage b" controlled by a valve 0 which is carried by the float 0.These partsmay be of any usual or approved construction. At the bottomof the ,iioat chamber 1) isan outlet controlled by the needle valve (1and leading by way of a tube d to the spray nozzle e. This nozzle isstationary relatively to the parts a, b, and is located axially withrespect to the mixing chamber a, the latter being tubular. Within saidmixing chamber is movable vertically the Venturi tube f the contractionor throat of which is but slightly wider than the largest diameter ofthe spray nozzle e. The Venturi tube J is connected rigidly with anannular piston g movable ina suitable cylindrical portion a of thecasing. A spring h tends to move the Venturi tube 1 toward the spraynozzle e, the corresponding limit position being indicated by dottedlines, while the position indicated by full in detail in Figs. 2 and 3.Small tubes I extend ber a and beyond the throttle valve k to the enginemanifold. I-have indicated a throttle valve of the customary pivotedtype, but do not wish to restrict myself thereto. The Venturi tube 1 maybe provided with ducts f to avoid trapping a body of air between thepiston g and the upper end of the cylinder 11'.

The needle valve (1 is connected to move in unison with the Venturitube 1. For this purpose, a rod 1 is secured to the piston g and isconnected with the needle valveby a suitable clamp 7'. Preferably theconnection is an adjustable one, which may be accomplished by threadingthe lower end of the rod 12 into the piston 9, while the upper end ofsaid rod is mounted in the clamp 1' in such a manner that such rod mayrotate in the clamp without moving vertically in relation thereto.

The construction of the spray nozzle is shown lengthwise into the spraynozzle at a distance from its axis from the lower surface. of saidnozzle, said tubes terminating above a partition m located within thespray nozzle. From the chamber -m located 'above said partition, the airpasses through openings 11. into a tubular member n located axiallywithin the spray nozzle. This member'n is closed-at the upper end andpreferably also at its lower end. The passage d communicates with theinterior of the member 11. by openings n" located below the partition mand below the level x:c of the fuel as maintained by the float'c. Theupper end of the member n is screwed into the spray nozzle e, a slotbeing shown in Figs. 2 and 3 for the application of a screw driver toapply or remove said tubular member n. Thus different members n may besubstituted in accordance with the character of the fuel and withother-conditions varying in individual cases, the members 11. varying asregards their length, or the arrangement of their openings n, n, orboth. Below the partition m is located a chamber m' provided with anannular series of jet openings 0 which are located at the upper portionof the spray nozzle, slightly above its greatest diameter. j

The suction of the engine will tend'to draw the Venturi tube away fromthe spray nozzle and to enlarge the area of the annular passage betweensaid nozzle and the Venturi tube, while the spring h will tend to movethe Venturi tube f in the opposite direction. The amount of enginesuction depends upon the position of the throttle valve It. When theVenturi tube is in thelowermost position indicated by the dotted lines,the needle valve (1 will be almost closed and the fuel supply will becorrespondingly cut down. As soon as the engine is running, its suction,de-

pending upon the position of the throttle 'valvek,

will cause the Venturi tube fto shift from the position indicated bydotted lines more or less toward the position shown in. full lines. Atthe same time the needle valve (1 will be opened wider to supply fuelmore abundantly to the spray nozzle e. Air entering at a will passaround the spray nozzle, and-a portion of such air will enter the tubesl, passing into the chamber m and through the openings 11. into thetubular memvalve or the engine suction varies, there will be.

corresponding automatic variations in the position of the Venturi tube,1 and of the needle valve d. The adjustable connection i'enables theneedle valve (1 to be given the proper position relatively to the pistong and Venturi tube f. The main object of making the rod 1' adjustable,however, is to vary or adjust the point at which the downward movementof the Venturi tube I will be stopped. It will be evident from Fig. 1,that the downward movement of the Venturi tube is limited bythe'engagement of the lower end of the rod 2' with the bottom flange ofthe cylinder a. Therefore, by adjusting the rod 1'. up or downrelatively to the piston ,g, the point at which the Venturi tube I willbe stopped inits downward movement, can be adjusted. Preferably, when inits lowermost position, the narrowest portion or throat of the Venturitube 1 will be at the level of the widest portion of the spray nozzle s,as indicaed by dotted lines in Fig. 1. Instead of having the lower endof the rod 2' act as a stop for limiting downward motion of the Venturitube, I might. make the throat of said tube of slightly smaller diameterthan the widest portion of the spray nozzle e, in which case thedownward motion of the Venturi tube would be stopped'by the said tubecoming to rest on the spray nozzle.

' The upward motion of the Venturi tube is limited by the engagement ofthe piston g with the upper' end of the cylinder a, and in saiduppermost position, the cross-section of the annular space or passagebetween the spray nozzle and the Venturi tube is preferably exactly orapproximately equal to the cross section of the passage of the Venturitube at its narrowest portion or throat.

During the operation of an internal combus tion engine, there is, exceptwhen the engine is I utilize this difference of pressures'while theengine is running, to

extend past the throttle to said regulating device. The pressuredifference, except when running under full load, amounts to one-halfatmosphere or more, upon an average. In engines of the customaryconstruction, the suction effect is prac tically destroyed at thethrottle valve and does not extend beyondit.

Even without the use of a spring such as h, gravity would tend to bringthe Venturi tube f andthe needle valve d to their lowermost position,and if the Venturi tube and the parts connected therewith are made ofsufficient weight, the spring It might be dispensed with. I prefer,however, to employ such a spring, and preferably such spring is under asubstantial tension even when the piston g is in its lowermost position,so

that when said pistonmoves upward, the tension of the spring will beincreased but slightly. With this arrangement, a suflicient suction willbe obtained even when the engine is running at low speed without anyload,,to secure within the spray nozzle the pressure difference requiredfor a thorough spraying or atomizing action even when the amount of fuelfed is relatively small. The fuel is ejected through the openingslocated below' the partition m. When a spring is employed, the suctioneffect on the Venturi tube will not be quite constant, owing to theslight increase in spring tension which occurs when the Venturi tubemoves upward. If a perfectly constant suction effect is desired, Iemploy the construction referred to above, in which the spring h isdispensed with, so that the suction effect is counteracted by a constantforce, viz. the weight 4 of the, Venturi tube and the parts connectedtherewith. When using a Venturi tube without a spring such as h, theweight of said tube and the parts connected therewith will be made. tojust counterbalance the suction effect on the surface of the Venturitube' when the engine is running at full load. The distance to which theVenturi tube will rise from its lowermost position, and therefore. theamount of fuel-and-air mixture passing through said tube will depend onthe position of the throttle valve is at any particular moment. Thespeed with which such mixture travels will therefore remain constant,and the amount of fuel passing through the spray nozzle will be indirect ratio to the cross-section of thefuel passage controlled by theneedle valve d. The device therefore will produce an efficientregulation without the aid of .any additional nozzles, pumps, or otherauxiliaries, and qthe construction is not only simplified, but will workpositively under all conditions.

When crude oil is employed as the fuel, in which case a relatively highpressure difference is required to produce the necessary spraying of thefuel, I employ a spring h of higher tension, or, if no spring isemployed, a Venturi tube of greater weigl'it than when employing morevolatile fuel.

It is well understood that, as in usual practice, the throttle valve iswill, even in its so-called closed position, leave a sufiicientclearance for air to pass from the'inlet a" through the interior airchannels of the spray nozzle, thus supplying a sufficient amount of fueleven under these special conditions (no load).

The ducts f not'only prevent a trapping of air in the cylinder a, butalsoper'mit the suction existing within the air tube to extend to thein-- terior of the cylinder a whereby the effect will be increased sincethe upward suction .will be exertednot only on the Venturi tube I, buton the piston g as well. The piston furthermore serves as a dash pot toprevent fluttering of the Venturi tube in accordance with the pulsationsin the suction effect exerted by the engine.

The air which enters the spray nozzle e through the (preferably taperedor conical) tubes 1 is firstconducted to the chamber m'which is situatedabove the fuel level m:c. Such air then passes down into the fuelthrough the tubular member n and its openings 12", which latter arelocated below the fuel level. This insures "a thorough mixture of airand fuel which mixture passes out of the chamber m" through the openings0 which form an annular series of jets. These openings are located insuch a manner'that even with the Venturi-tube f in its lowermostposition, the outlets of the jet openings 0 will be unobstructed.-

The aggregate cross section of the inlets of the tubes or channels I isgreater than the, aggregate cross. section of the outlets n" throughwhich the air passes from said channels to the fuel, so as to increasethe pressure of the air within said channels. The outlets n" arepreferably in the same axial planes with the respective jet openings 0.The tubular member n is removable not only for the purpose ofsubstituting different members of different character according todifferent circumstances, but also to enablethe level of the fuel withinthe spray nozzle e to be observed so as to properly set the floatcontrolled valve 0'.

While in Fig. 1 the float chamber his shown as located toone side of themixing chamber a, it will be understood that any other suitablearrangement may be employed.

Figs. 4 and 5 illustratetwo constructions in which the carburetoroperates without a float. In Fig. 4 the construction of the verticallymovable Venturi tube is substantially the same as described above,except that such tube is not connected 'with a separate piston workingin a dash pot. The needle valve d is secured directly to the Venturitube and controls the passage of fuel from a supply pipe d" to the spraynozzle e which latter may be of exactly the same construction as shownin Figs. 1, 2 and 3. In this particular construction there is no springtending to bring the Venturi tube to its lowermost position, but onlythe weight of said tube and the parts connected therewith is relied tooppose the suction effect of the engine. The needle valve is in thiscase shown as provided with a head (1 which in the lowermost positionof. the Venturi tube will rest upon a seat and form a valve to shut offthe pas-t sage of fuel to the spray nozzle. In addition to the needlevalve (1 the Venturi tube in this case also carries a tapering(initially closed) valve d which controls an air inlet opening d Thesuction will cause the Venturi tube f to rise more or less and suchmovement will effect a corresponding setting both of the fuel valve dand of the air valve d so that in all cases the proper relation ismaintained between the supply of air and the supply of fuel.

In Fig. 5, the Venturi tube 1" is stationary and 18 formed with a valveseat adapted to be engaged bythe spray nozzle e'when the latter is inits lowermost position, the spray nozzle in this case being movablevertically upon the axial end of the fuel supply pipe d. Thisconstruction has certam advantages over those described above, in thatthere are no surfaces in frictional engagement with each other duringthe vertical move ment. The needle valve 41 is in this case secured tothe spray nozzle e, to extend into the upp'erend of the fuel supply pipe41. Preferably the needle valve is removable, as'by screwing it into thespray nozzle, so that different kinds of needle valves may besubstituted in accordance with the particular type of fuel or engineemployed. The spray nozzle has an annular series of jet openings '0' solocated that even in the lowermost position of the spray nozzle, theoutlets of said openings will be unobstructed. Fuel passes from thesupply tube 11' to said openings 0' through an auxiliary mixing chamberm in the spray nozzle e, while whenever said nozzle israised from itslowermost position, a supplementary air supply is admitted to saidchamber through openings 1 in the vertical stem or cylinder e of thespray nozzle. The spray nozzle may be held in its lowermost position (inwhich the openings Z are closed) either simply by gravity, or with theaid of a I spring h and preferably, asin the form first described, saidspring is under tension even when the spray nozzle is in its lowermostposition. In

dash pot p surrounding the fuel'supply pipe ,d,

' said dash pot working in conjunction withv an when the engine is notrunning, rests on a valve annular piston 6 located at the lower end ofthe stern e and moving inunison therewith, the spring h being inengagement with said piston and with a corresponding abutment surfacenear the upper end of the fuel supply pipe d.

In order to prevent fluttering, I found that a;

spring h of relatively considerable stiffness is required, or, if nospring is employed, a relatively considerable weight must be given tothe spray nozzle and the parts connected therewith. The resistanceopposed by these parts would, however, be an objectionable feature atsuch times as the engine is working under full load, and it is thereforedesirable that when the engine is working at full load, the resistanceopposed by thespray nozzle and the parts connected therewith should beeliminated. For this purpose, I have shown the throttle valve k asprovided with a projection k adapted to enter an opening e in a lug atthe top of the spray nozzle, said projection being inclined so that whenit enters the said opening e with the throttle valve in its fully openposition, the said throttle valve will lift the spray nozzle to a higherposition than the suction of the engine will do.

The needle valve illustrated in Fig. 5 is of a special novel and usefulshape shown more clearly in the enlarged view Fig. 6. This valve has anenlarged, preferably conical portion d which,

seat at the upper end of the fuel supply pipe d andcloses the fueloutlet. When the valve rises off its seat, the fuel issuing at aconsiderable speed is finely distributed radially in all directions bythe flaring surface of the valve portion 11 The air passing through theopenings Z and forming, owing to its higher speed, an annular jetsurrounding the fuel jet, likewise strikes said inclined or flaringsurface and becomes intimately mixed with the fuel; this preliminarymixture, occurring in the chamber m is then perfected when the mixture,issuing from the openings 0', meets the additional stream of air whichsurrounds the nozzle 6' within the tube f".

Preferably the nozzle e and the Venturi tube 1" are so constructed thatat the beginning of the upward (opening) movement of the nozzle,

when the engine is rgming idle, no air. will be allowed to pass aroundthe nozzle, but the only air admitted will be that flowing through theopenings Z. For this purpose, the Venturi tube I" will be made withashort cylindrical portion f immediately above the seat of the nozzlehead, and of a diameter almost equal to that of said head. Thus, whilethe engine is idling, the entire amount of air will pass through thenozzle head.

Preferably, in this case, the tapering end of the valve 01, below theenlargement d is made in two portions (1 d", of which the upper onetapers less than the lower one. The height of this upper portion dshould be equal to the height of the cylindrical portion f so that thelower edge of the portion (i will reach the level of the valve seat atthe upper end of the supply pipe at, at thesame time that the widestportion 7 will be increased (owing to the narrow end per-- tion 11rising to the level of the valve seat, as

in Fig. 5) at the same time that the air supply is increased by allowingair to pass around the nozzle head.

By a proper formation of the Venturi tube, I mayprevent the passage ofair around the nozzle head, at the beginning of the operation, even inconstructions of the type shown in'Figs. 1, 2 and 3. Thus, in Fig. 2, Ihave indicated a short cylindrical portion on the Venturi tube f, whichportion will have the same function as the portion I of Fig. 5; thatisto say,'the air passage around the nozzle head e will not be openeduntil. the widestportion of such head has risen above the cylindricalportion i and until that time air' will pass exclusively through thein-' only. in the upright position illustrated. More particularly, theymaybe used in an inverted position, so that bothair and fuel will streamdownwardly to the carburetor, which will increase the speed of theirflow and enhance the atomizing or spraying action, especially whenemploying a needle valve with a flaring surface such as shown at d inFig. 6. l

In Figs. 7 and 8, I have shown a form of my invention which isparticularly adapted for use in an inverted position, both the air andthe liquid fuel (gasoline) being fed downwardly to the throttle valve kand to the engine, and no float being necessary. The Venturi tube Fforms part of the carburetor body, the latter also having a cylindricalportion F, similar in function to the portion f of Fig. '5, the outeredge of the nozzle head M being adapted to slide, like a piston,alongcarburetor. Air entering the carburetor body at a has access,through openings L on the nozzle head, to an interior chamber M formedin the said head above a horizontal or approximately horizontal wall orpartition M'-', said chamber extending to the edge or peripheral portionof the head M. The latter is made integral, 'or connected rigidly, witha tubular member 'M arranged to slide up and down along the outersurface of the fuel supply pipe T. Thechamber M is provided, adjacent tothe outer edge of the wall M, with openings Q through which fuel and airwillbe discharged in jets into the main mixing chamber P. The upper endof the tubular member M is made with a flange M against which bears oneend of a coiled spring H, the other end of said spring engaging anabutment A. This abutment.

might be stationary, and in any event is stationary during the ordinaryoperation of the engine,

but may be adjustable in the manner and for the purpose explained below.The spring H tends to keep the needle valve D on its seat 8. When saidvalve is seated, the edge-of the nozzle head M isin registry with the.cylindrical portion F, so 'that no air can pass from the inlet a" to'themixing chamber P by the direct path around the, nozzle head, adjacent tosaid portion F. When "theneed le valve is seated, the openings L will beclosed entirely by the adjacent portions of they supply pipe 'I'. Assoon as the needle valve opens, as it will when the nozzle head M movesdownward in response to engine suction, the openings L and 0 will beuncovered partly or fully, thus providing a path for the passage of airfrom the inlet a" through the openings L to the chamber M, and from thelatter through the openings 0 into the mixing chamber P. As soon as theneedle valve D opens, liquid fuel will drop by gravity from the supplypipe T and spread in a thin film on the horizontal partition M", suchliquid flowing outwardly and its upper surface being exposed to thestream of air passing over it from the openings L to the openings 0.During this initial stage (at the time of starting the engine) thecarburetor will therefore act as a surface carburetor. When the needlevalve opens to a greater extent, the film of liquid fuel will be ofsufficient depth to cover the outlet openings 0, and at that time airentering through the openings'L will pass through the liquid, and notsimply over it. This will result in a spraying action. As long as theouter edge of the nozzle head M is in registry with the cylindricalportion F, air from the inlet a', passes to the chamber P exclusivelythrough the interior chamber M' of the nozzle head. When however thenozzle head moves down sumciently to clear said' cylindrical portion F,an additional, wider path, externally of the nozzle head and around itsentire edge, is opened for the passage of air from the inlet a" directlyto the mixing chamber P. The air flowing through this additional pathwill strike the jets of fuel, or fuel and air, issuing from the openings0, and thus a very thorough mixing of air and fuel will be insured. Itwill be understoodthat the tapering needle valve D, and particularly theconical seating portion D thereof, will cause the fuel is-'- suing fromthe pipe T to be deflected and distributed radially or outwardly towardall portions of the periphery of the interior chamber M. The

fuel thus thrown outwardly will impinge against the opposing wall M -ofsaid chamber and will thus be broken up into a spray which will be thefiner, the greater the diameter of the nozzle head. The inlets L form anannular series of openings, or virtually an annular opening throughwhich air enters the chamber M. Since air has a smaller specific gravitythan the fuel, the current of air will travel at a much greater velocitythan the fuel, and striking the finely-divided film of fuel at this highvelocity, will atomizeor spray the same. The air, which at first travelsinwardly at the openings L, then takes an outward course, insubstantially radial directions, in response to the suction exertedoutwardly at the openings 0. The impact of the air on the inner wall ofthe head M and on the fuel will cause a considerable whirling action,which in turn produces heat, the carbureting or vaporizing action beingthereby assisted materially. A very efficient mixture of air and fuel isthe result.

The upward or closing movement of thenozzle head M is limited solely bythe engagement of I the needle valve portion D with its seat S.

' Therefore, when the engine is notrunning, the

spring H. will positively insure shutting off the fuel supply at thevalve seat S. When the engine is idling,-the edge of the nozzlehead willbe in registry with the cylindrical portion F, and

air pass only through the inner path L, M, O as described above. Duringnormal running under load, the nozzle head will be in a position lowenough to allow air to stream externally of the said head, through theopening formed by said portion F, so that during normal running,- airwill pass both externally of the nozzle head andthrough it, wherebythere is secured carbu retion resulting from surface action combinedwith a Spraying effect.

the engine is cranked over, but. fails'to start, the

liquid fuel which has spread over the partition M" will evaporate, atleast in part, during the interval betweenv the'first cranking of theengine andthe next, so thaitwhen the next crank ing causes a furtheramount of fuel to be fed from the supply pipe T, a richer mixture willbe obtained, it being well-known that a richer mixture makes the enginestart more easily.

Practical experience with this improved carburetor has shown that,without any change in the size. of the passages for air and fuel, aricher mixture will be obtained if the tension of the spring H .isincreased. It is well-known that in carburetors of usual construction,seasonal or other temperature changes in the surrounding air will causethe mixture to become leaner (in cold weather) or richer (in warmweather), and to counteract this, resort has been had to thesubstitution of different nozzles for summer and winter userespectively. I have found that with my improved carburetor, anadjustment to meet different seasonal conditions can be made rea'dily,without any exchange of nozzles, but simply by varying the tension ofthe spring H, thereby obtaining a uniform mixture under all temperatureconditions. This adjustment of the spring tensionmay also be employed tomeet different conditions resulting from the manner of feeding the fuelto the carburetor. When for instance a gravity feed is employed, thespring suction or vacuum feed is used. .Furthermore, practical trialshave shown that the vaporizing action is increased materially when theinitial tension of the spring is relatively high, and quickeracceleration and response is thus obtained. I have therefore found itdesirable to give the spring an initial tension high enough to cause theair velocity both within and around the nozzle head, to be greater atlow engine speeds than when running under full load. In order that this'high spring tension may not oppose an undue resistance when running atfull load, I may employ an;-arrangement such as described above withreference to Fig. 5, where the throttle valve in its full open positioncom presses the spring to a greater extent than the mere suction effectof the engine would do and holds the needle valve open against such in-,creased spring. tension; or instead of this, I

might provide means for releasing the spring fastening and therebyreducing or suppressing the spring tension.'

Any appropriate means maybe provided for 2140 Figs. '7

The abutment A is constituted bya flange atthe bottom of a sleeve Bsurrounding the spring H and suitably guided for vertical movement inthecalrburetor body. At diametricallyopposite points, saidsleeve' hastwo pins 3' projecting into slots in the fork members C of a lever Cswing-I ,ing on a stationary .ful'crumC". The outer end of the lever isexposed and thus readily accessible for manipulation. A set screw E orother suitable means serves for locking the lever and the abutmentagainst accidental movement. It be obvious that moving the free end ofthe lever C upward will reduce the initial tension of the spring H,while a downward movement of said lever end will produce the oppositeresult.

It will be seen that in Figs. 7 and 8 the car.- buretor is used as adown-draft carburetor, differing however from other carburetors of thedown-draft type in that not only the air but the fuel as well travels ina downward direction, and also in other respects.

While the carburetor shown in Figs. 7 and 8 will generally be employedas a fioatless carburetor, it may, if preferred, be used in conjunctionwith a float-controlled fuelsupply, particularly if the fuel is fed fromabove and it'is desired to avoid the slight fluctuations due to changesof the fuel level in themain fuel tank.

Practical trial of my improved carburetor on a motor car having amaximum speed of over 60 miles per hour has shown that while driving inhighgear, the speed could be throttled down to two miles per hour andagain increased without causing the engine to miss or stall.

Various modifications may be made without departing from the nature ofmy invention as se forth in the appended claims.

I claim:

1. A carburetor provided with two members movable relatively to eachother, one of said'members being an air tube of the Venturi type, andthe other a fuel spray nozzle located within said tube, in combinationwith a throttle valve controlling the passage of the air-and-fuelmixture to the engine, one of said members being movable in response tothe engine suction and means on said throttle valve to engage the saidmovable member in the full-open position of said throttle and move saidmember beyond the position which it will be given by suction alone.

2. In a carburetor, a movable spray nozzle, an air-supply channelleading through said nozzle, and a member surrounding the nozzle andforming therewith an external air-supply channel surrounding the nozzle,the nozzle constituting a valve for closing said external channel, andsaid surrounding member being so formed that the external channel willnot be opened for the passage of air until the nozzle has moved apredetermined distance from its extreme closing position, said spraynozzle having afuel-supply channel with a valve seat at its dischargeend, and said nozzle being provided with a needle valve having anenlarged portion fitted to said valve seat, and a smaller end portionextending from said enlarged portion into the fuel-supply channel, saidend portion being tapered. lightly adjacent to said enlarged portion,and more strongly toward its free extremity, the length of saidlightlytapered portion corresponding to the length of that portion inthe movement of the nozzle during which the external air-channel remainsclosed.

3. Ina carburetor, a fuel supply conduit having a valve seat at itsdischarge end, a movable spray nozzle provided with a valve co-operatingwith said seat, said nozzle having an internal chamber arranged toreceive fuel when said valve is open, and provided with outlets for thedischarge of air and fuel, said internal chamber having a wall on whichthe fuel is adapted to spread into a film, said chamber also having airinlets so located that upon a slight opening of the valve 9. surfacecarburetion will take place and that upon the valve opening more fully,a spraying of the fuel will be obtained.

4. A .carburetor according to claim 3, in which the internal chamberextends substantially throughout thewidth of thenozzle, and in which theoutlets are located at the periphery of the nozzle.-

5. A carburetor according to claim 3, in which the valve seat and thevalve fitting it are tapered in such a direction as to spread the fuelfrom the discharge end of the fuel supply conduit radially within thechamber of the nozzle.

6. A carburetor according to claim 3, in which the air inlet surroundsthe discharge end of the fuel supply conduit, the supply of air varyingautomatically in response to. the suction exerted at the outlet of thecarburetor.

'7. A carburetor according to claim 3, in which the discharge end of thefuel supply conduit is directed downwardly to the internal chamber ofthe spray nozzle.

8. In a carburetor, a movable spray nozzle provided with an internalchamber having peripheral outlets and air inlets locatednearer to theaxis of said nozzle than said outlets, a stationany member surroundingsaid nozzle and having a portion adjacent to the periphery of saidnozzle when the latter is in its initial position,

a stationary fuel supply channel having its outlet within said chamberand provided with a valve seat at such outlet, the internal chamber ofthe spray nozzle having a transverse wall andto be vaporized therein bythe air entering said inlets and to pass out with such air through saidperipheral outlets during the initial movement of the spray nozzle,whileupon further movement of said nozzle the peripheral portion thereof willcome away from the adjacent portionof the stationary member and open an'external channel for the passage of air around said nozzle. Y

' CHRISTIAN LORENZEN.

